Air gauge

Application filed November 24, 1928. Serial No. 321,669.

Our invention relates to pressure gauges for pneumatic tires.

An object of the same is to provide a pressure gauge whereby the pressure in a pneu. matic tire may be read at all times and will ’’ permit the passage of air into the tire from a suitable source of pressure or the release of the tire pressure from the latter when desired. .

_υ The invention further provides an air gauge which is permanently associated with the usual pneumatic tire stem and is of such construction as to reduce its liability to breakage to a minimum.

_;- Another object of the invention is to provide a pressure gauge of this character which will normally hold the usual check valve in the tire stem in open position to permit tire pressure to be communicated to a pressure n,-, indicator mechanism, but when removed from the tire stem will permit the check valve to seat in the usual manner thus preventing the loss of tire pressure.

With the preceding and other objects and .>-, advantages in mind, the invention consists in the novel combination of elements, constructions and arrangements of parts and operations to be hereinafter specifically referred to, claimed and illustrated in the accompany30 ing drawings, wherein:

Figure 1 is a fragmentary side elevation of a pneumatic tire having our invention associated therewith;

Figure 2 is a longitudinal sectional view of 3-, the same taken on line 2—2 of Figure 1; and

Figure 3 is a transverse section taken on line3—3 of Figure 2.

Referring to the invention in detail, a cylinder 5 whose bottom is formed with a hollow 40 central nipple 6 terminating in an annular flange 7 is provided. A flanged nut 8 is loosely received on the nipple and held against displacement therefrom by the annular flange 7. Cooperating with the nut 8 in 45 holding the casing in operative position is a bushing 9 having screw threaded engagement with a conventional tire stem 10 at the upper end thereof which has threaded engagement with the nut 8.

Formed with the bottom of the casing and ₅₀extending longitudinally and centrally thereof is a post 11 having a longitudinal bore 12 extending its entire length. At its upper end, this bore 12 is enlarged and receives a conventional check valve 13 which ₆₅is normally closed to the atmosphere. At its lower end, this bore 12 communicates with a by-pass 14 provided in the bottom of the cylinder and leading from the hollow nipple. The by-pass 14 communicates with a conduit _eo15 formed' in an upstanding enlargement 16 cast with the inner face of the bottom of the cylinder.

For the purpose of indicating the pressure contents of a tire tube, from which the: stem ₆₅10 projects, a pressure responsive element in the form of a helically coiled resilient, tube 17 is provided. The coiled tube 17 encircles the post 11 and has its lower extremity welded or otherwise secured to the enlargement 16 and communicating with the conduit 15. The opposite end of the coiled tube is closed so that when pneumatic pressure flows into the tube, the latter will be expanded according to the air pressure contained in the ₇.-, tire tube. Fixed to the upper end-most convolutions of the tube is a laterally extending L-shaped indicating finger 18 which is movable over a semi-circular graduated scale 19 disposed to one side of a semi-circular slot or :₈o sight opening 20 provided in the upper end of the cylinder.

The scale 19 is formed with an offset attaching portion 21 which is secured to the walls of the cylinder below the; opening. 19 ^85 so as to support the scale in spaced relation to the cylinder walls so that the vertical: leg of the indicating element may move between the scale and cylinder walls. ..

In order to permit pneumatic pressure to BO

1,855,088 flow from the valve stem 10 and into the coiled tube, a boss 22 is formed upon the under face of the cylinder bottom and is located centrally of the hollow nipple to en⁵ gage the usual check valve 10α in the tire stem to hold the latter in open position.

In order to preclude the passage of dirt and other foreign matter into the cylinder by way of the slot 20, a relatively heavy glass ¹⁰ annulus 23 is received in the upper end of the cylinder in transverse alinement with the slot 20. The glass annulus 23 is clamped between an annular internal shoulder 24 provided upon the interior of the cylinder and a ¹⁵ closure cap 25 having threaded engagement with the cylinder. Packing elements 26 are arranged upon the opposite faces of the annulus to protect the same against breakage. A central threaded opening 27 is provided in ²⁰ the closure and has threaded engagement with the threaded projecting end 28 of the post to lend rigidity to the latter at this point.

With a tire gauge thus constructed, the ²⁵ pneumatic pressure will be always communicated to the pressure responsive element and thus indicate the tire pressure at all times.

. When it is desired to increase the tire pres³⁰ sure, the usual air hose chuck is positioned on the projecting end 28 of the post and in so doing, the valve 13 is depressed to allow air pressure to pass through the bore 12 and into the tire stem. In the event that it is de³⁵ sired to release some of the pressure from the tire, the valve 13 will be held depressed in the usual manner.